You know all those people who said shooters couldn’t be done on the iPhone?Gameloft weren’t listening.They proved them wrong with Modern Combat, their take on Call of Duty, then with N.O.V.A, the iPhone’s own Halo.

Since then they’ve released a sequel to Modern Combat which improved on the original in every single way.Not wanting to stop there, now they’ve released N.O.V.A. 2 – Near Orbital Vanguard Alliance HD, but will it be worth the upgrade?

The answer, for those of you with attention spans shorter than the end of this review, is yes.What’s more, it’s clear from the very first second that you jump off your transport ship and enter the first battle.Playing through the training section and the first mission on an iPhone 3GS, both the attention to detail and refinement of the controls are clear to see.Movement and aiming are far smoother than before and the enemies seem that much smarter.But pop N.O.V.A. 2 on an iPhone 4 and you’ll be blown away.Control is smoother and far easier to aim with and the Retina Display graphics blow most other games out of the water.

Whichever device you have, though, N.O.V.A. 2 will involve a lot of firefighting over 12 levels with some impressive AI.Just as with Halo, enemies now duck and try to flank you as you hide behind a pillar for cover.Larger enemies, such as the impressive mechs, will just wade in and fire.But you have a secret weapon on your side.

New tools help you in your fight against the oncoming waves.At first this is a freeze blast which, when aimed correctly, can freeze your enemies in place for a few seconds while you empty a few more bullets into them.Later on you get a ‘bullet time’ effect and a saw disc.Getting used to these is important as it will vastly increase your chances of making it through the hordes of alien/human alliance armies in one piece.